Artistic depiction of paramecia with artificial cilia: Chiral, unidirectional molecular switches mounted on surfaces are the prerequisite for inducing cilia driven directed motion. Scientists from Kiel transformed simple azobenzenes to chiral switches equipped with a molecular platform to mount them on gold surfaces. This bionic emulation of a billions of years old biological transportation system might be used in nano fabrication in the future.

Illustration/Copyright: Herges

Abstract:
Cilia, or ciliated epithelia, cover our respiratory tract like a lawn. In our pharynx and nasal mucosa they are responsible for continuously transporting mucus and particles embedded therein towards our throat. (except for heavy smokers, whose cilia where destroyed by nicotine and tar.) Tobias Tellkamp and Professor Rainer Herges have now come one step closer to their aim of artificially reproducing this biological transport system with switchable molecules.

Artificial cilia: Scientists from Kiel University develop nano-structured transportation system

Kiel, Germany | Posted on July 4th, 2014

Molecules that wiggle when exposed to light are known for a long time. But directed movement had not been possible up until now because back and forth movement cancel each other. To achieve a net displacement, the cilia should beat only to one side. Applying a trick within the molecular construction, the chemists of Kiel University's Collaborative Research Centre 677 "Function by Switching" solved this problem: Moreover, to get those molecular cilia up and running, the scientists fixed them on a surface. "We attached a kind of molecular suction cup onto the switches", project leader Herges explains.

Studies have shown that this suction cup adheres very well to gold surfaces. The team of scientists observed that the molecules self-assemble autonomously on the surface, densely packed, side by side like oranges on a shelf. "The suction cups adhere to the surface but they are still mobile and attract one another", explains doctoral candidate Tellkamp. In this way, an artificial epithelium is formed.

The next logical step is to find out if the artificial epithelium works much in the same way as our nasal mucosa. In collaboration with Prof. Olaf Magnussen in the Physics Department of Kiel University atomic force microscopy (AFM) will be used to visualize the light driven, directed transport of nanoscopic particles.

The recent findings are particularly interesting, not only with respect to fundamental research. With artificially ciliated epithelia, a molecular nano-fabrication seems possible - machines of molecular size would build other machines by positioning chemical products specifically and precisely. Entire production plants could thus fit onto a tiny chip. Other conceivable fields of application include artificial organelles equipped with molecular cilia that are controlled by an external stimulus; or in the more distant future, they could operate autonomously within the bloodstream and carry drugs to the site of a disease.

About Christian-Albrechts-Universitaet zu KielWhen Duke Christian Albrecht of Holstein-Gottorp decided to found a university in 1665, the Thirty Years' War was over. The State required well-educated young men for service to government, who were to graduate from the new university. 140 students enrolled in the initially established faculties of Theology, Law, Medicine and Philosophy.

The University currently teaches over 24,000 women and men and the range of subjects on offer is spread over eight faculties. In addition to the original faculties, the faculties of Agricultural and Nutritional Science, Mathematics and Natural Sciences, Business, Economics and Social Sciences and, the newest faculty, the Faculty of Engineering are integrated into the university. Where once Max Planck and Heinrich Hertz worked, around 700 academics now pass on their knowledge to students from Germany and across the Globe.